CVD aliasing: A CCE issue?

[SatStorm]

Over the last months, I keep reading emails and posts, for an aliasing and a distortion effect when you backup a DVD movie to CVD. Honestly, I never saw it at my encodings, except with some low pic mjpeg grabbs (17 or less set), which looked like a pixel distortion all over picture, but again, nothing like that aliasing in the picture some users keep reporting.
After some tests and many user reports, for a while looked like that this was a greater issue to NTSC backups than PAL ones.

The past 2 weeks, I had a good conversation with other enthusiasts of our hobby, for this matter. All of them was CCE users from all over the world and most of them used exclusivly DVD2SVCD to back up DVDs.
I use mostly TMPGenc plus with my DVB source to encode to CVD/SVCD and sometimes xSVCD, since I don't buy much DVDs and if I do, I don't back up them (I wait to back up them on DVD-Rs, next year, which I planning to buy my own 4X dvd recorder). Anyway, after suggestions, I backed up to CVD my spiderman R2 DVD, using DVD2SVCD and an old demo of CCE 2.5 it happens to own for a long time now (since spain, if you know what I mean ). I encoded the movie to CVD with 3 pass VBR, which is the most common for quality freaks.

For the very first time, I saw to the resulting CVD that aliasing some users discrube. Terrible...

Just to be sure that wasn't the movie, I re-encode my DVD with the combination of DVD2AVI & TMPGEnc plus 2.59 (as I do the few times I back up my DVDs), with the same settings of CCE but with 2 pass VBR, since TMPGenc don't have more passes.
The result was a perfection, the best 2-CD CVD back up I ever did, thing which also rise the fact of the TMPGenc plus improvment at the latest built.

So, it is obvious that this aliasing of CVD is a result of a bad setup of DVD2SVCD, or a bad support of CVD by CCE. Unfortunatelly, my free time is over, and I don't have time to read the related doom9 forums, which I am sure they have already solution for this thing.
And I strongly believe that many users wont' do it eather, that's why I point the problem here, in this post.

For now, I can simply propose to all those enthusiast having probs with CVD, like this aliasing and distortion of the picture, for once do a encode with tmpgenc and compare the results.
The bottom line is that you don't have aliasing probs or pixel distortion with TMPGenc Plus. Since I don't use CCE that much, I don't know how that is fixed with this encoder. But the aliasing and distortion ain't there because of CVD nature. And that is what I also want to point.

I'll test further when I have time again (in about a month). Since then, any posting for the subject is very welcome!

[SatStorm]

also it seems that there was a problem with my post, or I press something without understanding during the uploading.
If it doulbeposted somewhere, moderators please delete it!
Sorry in Advance!

[adam]

Since I don't use CCE that much, I don't know how that is fixed with this encoder. But the aliasing and distortion ain't there because of CVD nature. And that is what I also want to point.

Well the thing that would be causing the aliasing would be whatever is doing the resizing, so if you are using DVD2SVCD then that is either the avisynth bicubic, billinear, or simpleresize filter. I believe that TMPGenc only uses billinear, or so I've been told. So if you want to setup cce most like TMPGenc then use that.

I haven't used DVD2SVCD in a while but I believe the default resize filter is simpleresize. This filter certainly isn't bad but it does cut corners compared to billinear and of course bicubic. Arguably, simple resize could cause aliasing during any amount of resize, not just with half D1 output.

If you really want to run some tests...

First make sure its not really CCE causing the aliasing. Do only your resizing in TMPGenc and frameserve to CCE. If no aliasing then you know it was the resizing filter and not CCE.

Then try frameserving via avisynth to TMPGenc using whatever filter you used in DVD2SVCD to do the resizing. If there is aliasing here than you can pretty much narrow it down to that filter.

For best results use the bicubic resizing filter when making CVD's, unless you can get away with using billinear without getting any aliasing. I've made lots of CVDs in both CCE and TMPGenc and on my tv I never see aliasing. However, on a my father's slightly higher quality television I do see some slight aliasing with CVDs.

[SatStorm]

Thanks Adam for your reply!
I'll test your suggestions as soon as possible!

[blah]

I got rid of aliasing by letting the fitcd compute the resize and crop parameters for me.
I've started to use the avisynth script that fitcd creates and I haven't got
any problems like stair case effect anymore.
Might not help others though. I use CCE for encoding.

[Yury Perschin]

Hi SatStorm!

One programm for one purpose. CCE good MPEG-2 encoder. Avisynth good frameserver. I use DVD2AVI and Avisynth as frameserver and use folowing script.

MPEG2Source("D:\Audio\music\matrix.d2v") #movie 720x480
Crop(8,0,704,480) #movie 704x480
HorizontalReduceBy2() #movie 352x480

If You use any resize method remember that if size increase (any dimension) You will not have problem, but if size reduce You have aliasing problem (Shanon-Kotelnikov theorem). HorizontalReduceBy2 make first lowpass filtering and after resizing.
If use this approach for MPEG-4 may use folowing script

MPEG2Source("D:\Audio\music\matrix.d2v") #movie 720x480
LanczosResize(960,640)#movie 960x640
Reduceby2()#480x320 movie

May use Generalconvolution for filtering and after resize, but this work slower (and request some knowledge about digital processing) than increase resize and ReduceBy2.

With kind regards Yury.

[blah]

Adam's right again.
It was a matter of resizing method.
I used simple resizing cause it is fast
works with svcd but cause aliasing with cvd.
Like Yury pointed out.

[SatStorm]

Yeah, I finally just tested myself also...
I made it like Adam pointed and now is OK. By the way, I found billinear better bicubic, but the difference is almost invisible in my TV. Maybe on other TV sets, bicubic is better...
It is always nice to learn tips and alternatives.
You see, because I use mainly TMPGenc for anything, my knowledge about CCE is, let say, average. It is a great encoder, I have to admit, but I somehow stuck with TMPGenc.... Maybe because I found the combo DVD2AVI/TMPGenc to easy to use with my DVB source. Maybe because I tested and tested TMPGEnc so many times, I almost know it 100% . I think I must write a manual for it.
To tell you the true, I found the difference between the latest TMPGenc and CCE minimal (for 1/2 D1 picture, for full CCIR still CCE is a clear winner), but CCE is way faster and do way better bitrate alocation per frame than TMPGenc on those extreme moving scenes.
Anyway, that's not the subject here.
Thanks again for your help!